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Cranial osteology of Hypoptophis (Aparallactinae: Atractaspididae: Caenophidia), with a discussion on the evolution of its fossorial adaptations
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Fossoriality evolved early in snakes, and has left its signature on the cranial morphology of many extinct Mesozoic and early Caenozoic forms. Knowledge of the cranial osteology of extant snakes is indispensable for associating the crania of extinct lineages with a particular mode of life; this applies to fossorial taxa as well. In the present work, we provide a detailed description of the cranium of Hypoptophis wilsonii, a member of the subfamily Aparallactinae, using micro-computed tomography (CT). This is also the first thorough micro-CT-based description of any snake assigned to this African subfamily of predominantly mildly venomous, fossorial, and elusive snakes. The cranium of Hypoptophis is adapted for a fossorial lifestyle, with increased consolidation of skull bones. Aparallactines show a tendency toward reduction of maxillary length by bringing the rear fangs forward. This development attains its pinnacle in the sister subfamily Atractaspidinae, in which the rear fang has become the “front fang” by a loss of the part of the maxilla lying ahead of the fang. These dentitional changes likely reflect adaptation to subdue prey in snug burrows. An endocast of the inner ear of Hypoptophis shows that this genus has the inner ear typical of fossorial snakes, with a large, globular sacculus. A phylogenetic analysis based on morphology recovers Hypoptophis as a sister taxon to Aparallactus. We also discuss the implications of our observations on the burrowing origin hypothesis of snakes.
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RBINS Staff Publications 2022
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Craniodental and postcranial morphology of Indohyaenodon raoi from the Early Eocene of India, and its implications for ecology, phylogeny, and biogeography of hyaenodontid mammals
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New remains of the early Eocene hyaenodontid Indohyaenodon raoi are described from the Vastan Lignite Mine in Gujarat, western India, including the first known rostrum, upper dentition, and postcrania, substantially expanding our knowledge of the species and providing insights into its functional morphology and relationships. Craniodental morphology suggests that I. raoi had a broad diet, including non-vertebrate material as well as flesh of a diversity of prey species. Postcranial morphology is broadly similar to that of other early hyaenodontids and suggests a scansorial locomotor repertoire. Dental morphology indicates that I. raoi is closely related to other South Asian hyaenodontids, with shared features including strong cingula, narrow premolars, and a reduced P4 protocone. We present the most comprehensive phylogenetic analysis of Hyaenodontidae to date, which corroborates this relationship but finds South Asian hyaenodontids to be the stem of a group that includes most African hyaenodontids. This and other higher-level relationships within Hyaenodontidae are, however, weakly supported, and substantially different alternative hypotheses of relationships are not significantly less parsimonious, reflecting strong character conflict. Factors contributing to this conflict include the isolation of hyaenodontid faunas on different continents during much of the Eocene, canalization and simplification of carnivorous dentitions, and a lack of non-dental material for critical hyaenodontid groups. The new phylogeny is consistent with either an African or an Asian origin for the group.
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RBINS Staff Publications
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Crassicauda boopis in a fin whale (Balaenoptera physalus) ship-struck in the eastern North Atlantic Ocean
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RBINS Staff Publications 2017
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Crinoid and ostracod succession within the early-Middle Frasnian interval in the Wietrznia quarry, Holy Cross Mountains
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RBINS Staff Publications
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Critical analysis of carnivoran mammal success in Europe during the Paleogene
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Why are we surrounded by only one group of placental carnivorous mammals (Carnivora: the present-day lions, dogs, bears, and seals among others) today, while at least three other groups of placental mammals (Hyaenodonta, Mesonychia, Oxyaenidae) were in competition with carnivorans 50 million years ago? Since the 1990s, palaeontologists have investigated the success of carnivoraform mammals (including Carnivora) and their crucial adaptations in detail. Analysis of the taxonomic and morphological diversification of these groups in the North American fossil record clearly showed that carnivoraforms outcompeted hyaenodonts and oxyaenids during the Eocene, specifically from around 50 Ma when carnivoraforms began to dominate. It has been suggested that the evolutionary success of carnivorans may have resulted from the broad range of dental adaptations (i.e., a broad variety of diets) conferred by the particular position of their carnassial teeth. Here we document the evolutionary history of the taxonomic diversity as well as the evolution of the body mass of carnivorous mammals that lived in Europe during the Paleogene (66–23 Ma). The results suggest that this competition was diametrically opposed in North America and Europe. Carnivoraforms actually did not become diversified in Europe during the Eocene and thus were not as taxonomically successful in Europe as in North America during that period. Moreover, when one considers body mass, the European hyaenodonts were distinctly more diversified than the carnivoraforms. The situation dramatically changed during the 'Grande Coupure' (around Eocene–Oligocene boundary; ca. 33.9 Ma). This transition corresponds to a major faunal turnover in Europe: during the earliest Oligocene global cooling (Oi-1) event, the Eocene endemic carnivorous fauna were replaced by immigrant taxa (hyaenodonts and carnivorans), mainly from Asia. The Oligocene fossil record shows a diversification of the carnivorans, whereas hyaenodonts were almost only represented by the hypercarnivorous genus Hyaenodon. However, two distinct periods can be discriminated in the Oligocene: the Rupelian was dominated by the Nimravidae and feliforms, while the Chattian was dominated by the caniformians (especially the Amphicyonidae and Ursidae). This turnover seems to be concomitant with the Latest Oligocene Warming and Microbunodon Event. Based on these results, one can hypothesize that the evolution of the European carnivorous mammals might have been profoundly driven by climate modifications (abiotic factors). Grant Information: This abstract is a contribution to the Belspo Brain Pioneer project BR/175/PI/CARNAGES funded by the Belgian Science Policy Office.
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RBINS Staff Publications 2018
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Crocidurobia faini n.sp. (Acariformes: Myobiidae), a new mite species prasitising shrews of the genus Crocidura Wagler (Soricomorpha: Soricidae) in DR Congo
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RBINS Staff Publications 2016
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Crop diversity and choices in the prehistory of South Eastern Europe: the archaeobotanical evidence from Greece and Bulgaria
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RBINS Staff Publications
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Crop diversity and choices in the prehistory of SE Europe: the archaeobotanical evidence from Greece and Bulgaria
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RBINS Staff Publications
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Crop diversity and choices in the prehistory of South Eastern Europe: the archaeobotanical evidence from Greece and Bulgaria In: Chevalier, A., Marinova, E, Pena-Cocharro, L. (eds.) Plants and People: choices and diversity through time
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No RBINS Staff publications
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Cross-calibration of different radar systems for monitoring nocturnal bird migration across Europe and the Near East
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RBINS Staff Publications 2018
